A large sized liquid crystal display (LCD) has recently attracted attention. With respect to large-sized LCDs, required therein is higher performance, for example, in viewing angle, contrast and stability in quality against environmental changes, compared to the required performance for conventional personal notebook computers or LCD monitors. Therefore, higher performance is also required for the polarizing plates used for the large sized LCD device or for the cellulose ester film used for the polarizing plate. Variations in retardation values have been observed in polarizing plates having thereon a retardation film, due to planned or unplanned changes in production conditions. Improvement for this problem has been desired specifically for large sized polarizing plates. Further, in order to improve the display performance of an LCD, a backlight unit has more commonly been provided behind the liquid crystal cell to directly illuminate the liquid crystal cell without using a light guide. However, in this direct illumination backlight system, when a LED backlight unit is used instead of a fluorescence tube backlight unit, variations in display quality tends to increase in accordance with the temperature increase caused by heat generated from the LED backlight unit, and further improvement specifically for obtaining displays exhibiting uniform contrast has been desired.
In order to obtain a display exhibiting long term stability of display quality and high productivity, disclosed is a retardation film of which moisture permeability is reduced (for, example, refer to Patent Document 1). Also, in order to obtain a display exhibiting limited light leakage caused by thermal distortion and high display quality, disclosed is a retardation film of which expansion coefficient due to moisture absorption is suppressed below a prescribed value (for example, refer to Patent Document 2). A polarizing plate exhibiting high durability even under a high humidity-high temperature condition is also disclosed, which is attained by controlling the diffusion coefficient of boric acid in the polarizing plate (for example, refer to Patent Document 3). However, these, improvements have not been fully satisfactory. In Patent Document 3, disclosed is a method to control the diffusion coefficient of boric acid by decreasing free volume in a cellulose acylate film, and in paragraph [0015] of this patent document, it is described that the free volume in a cellulose acylate film can be decreased by increasing the amount of crystals in the film. However, variations of retardation values of polarizing plates due to changes in producing conditions have not been fully reduced so far. Specifically, in an amorphous-like cellulose ester, for example, a mixed acid ester of cellulose such as cellulose acetate propionate, a notable effect has not been fully obtained.    Patent Document 1: Japanese Patent Publication Open to Public Inspection (hereafter referred to as JP-A) No. 2002-14230    Patent Document 2: JP-A No. 2002-71955    Patent document 3: JP-A No. 2004-279931